diff --git a/include/extern.h b/include/extern.h
index 2e1ad2a09..c8cabacc7 100644
--- a/include/extern.h
+++ b/include/extern.h
@@ -897,6 +897,7 @@ E void NDECL(domove);
 E boolean NDECL(overexertion);
 E void NDECL(invocation_message);
 E void NDECL(switch_terrain);
+E void FDECL(set_uinwater, (int));
 E boolean FDECL(pooleffects, (BOOLEAN_P));
 E void FDECL(spoteffects, (BOOLEAN_P));
 E char *FDECL(in_rooms, (XCHAR_P, XCHAR_P, int));
diff --git a/src/cmd.c b/src/cmd.c
index eebfee01d..2c5cbf34e 100644
--- a/src/cmd.c
+++ b/src/cmd.c
@@ -834,7 +834,7 @@ boolean pre, wiztower;
         (void) memset((genericptr_t)&g.updest, 0, sizeof (dest_area));
         u.ustuck = (struct monst *) 0;
         u.uswallow = u.uswldtim = 0;
-        u.uinwater = 0;
+        set_uinwater(0); /* u.uinwater = 0 */
         u.uundetected = 0; /* not hidden, even if means are available */
         dmonsfree(); /* purge dead monsters from 'fmon' */
 
diff --git a/src/detect.c b/src/detect.c
index 66d366aee..ca4179a7c 100644
--- a/src/detect.c
+++ b/src/detect.c
@@ -35,7 +35,7 @@ unconstrain_map()
     boolean res = u.uinwater || u.uburied || u.uswallow;
 
     /* bring Underwater, buried, or swallowed hero to normal map */
-    iflags.save_uinwater = u.uinwater, u.uinwater = 0;
+    iflags.save_uinwater = u.uinwater, u.uinwater = 0; /* bypass set_uinwater() */
     iflags.save_uburied  = u.uburied,  u.uburied  = 0;
     iflags.save_uswallow = u.uswallow, u.uswallow = 0;
 
@@ -46,7 +46,7 @@ unconstrain_map()
 static void
 reconstrain_map()
 {
-    u.uinwater = iflags.save_uinwater, iflags.save_uinwater = 0;
+    u.uinwater = iflags.save_uinwater, iflags.save_uinwater = 0; /* set_uinwater() */
     u.uburied  = iflags.save_uburied,  iflags.save_uburied  = 0;
     u.uswallow = iflags.save_uswallow, iflags.save_uswallow = 0;
 }
diff --git a/src/do.c b/src/do.c
index ef6bf5c6b..65bec769c 100644
--- a/src/do.c
+++ b/src/do.c
@@ -96,7 +96,7 @@ boolean pushing;
             }
 
             if (fills_up && u.uinwater && distu(rx, ry) == 0) {
-                u.uinwater = 0;
+                set_uinwater(0); /* u.uinwater = 0 */
                 docrt();
                 g.vision_full_recalc = 1;
                 You("find yourself on dry land again!");
@@ -1377,7 +1377,7 @@ boolean at_stairs, falling, portal;
     fill_pit(u.ux, u.uy);
     set_ustuck((struct monst *) 0); /* idem */
     u.uswallow = u.uswldtim = 0;
-    u.uinwater = 0;
+    set_uinwater(0); /* u.uinwater = 0 */
     u.uundetected = 0; /* not hidden, even if means are available */
     keepdogs(FALSE);
     recalc_mapseen(); /* recalculate map overview before we leave the level */
@@ -1495,7 +1495,7 @@ boolean at_stairs, falling, portal;
         oinit(); /* reassign level dependent obj probabilities */
     }
     reglyph_darkroom();
-    u.uinwater = 0;
+    set_uinwater(0); /* u.uinwater = 0 */
     /* do this prior to level-change pline messages */
     vision_reset();         /* clear old level's line-of-sight */
     g.vision_full_recalc = 0; /* don't let that reenable vision yet */
diff --git a/src/hack.c b/src/hack.c
index 33ddb5a2a..f8624ad6e 100644
--- a/src/hack.c
+++ b/src/hack.c
@@ -2086,6 +2086,14 @@ switch_terrain()
         g.context.botl = TRUE; /* update Lev/Fly status condition */
 }
 
+/* set or clear u.uinwater */
+void
+set_uinwater(in_out)
+int in_out;
+{
+    u.uinwater = in_out;
+}
+
 /* extracted from spoteffects; called by spoteffects to check for entering or
    leaving a pool of water/lava, and by moveloop to check for staying on one;
    returns true to skip rest of spoteffects */
@@ -2119,7 +2127,7 @@ boolean newspot;             /* true if called by spoteffects */
         if (!still_inwater) {
             boolean was_underwater = (Underwater && !Is_waterlevel(&u.uz));
 
-            u.uinwater = 0;       /* leave the water */
+            set_uinwater(0); /* u.uinwater = 0; leave the water */
             if (was_underwater) { /* restore vision */
                 docrt();
                 g.vision_full_recalc = 1;
diff --git a/src/objnam.c b/src/objnam.c
index b8bae7804..4565d3b28 100644
--- a/src/objnam.c
+++ b/src/objnam.c
@@ -3119,7 +3119,7 @@ int locked, trapped;
         /* hero started at <x,y> but might not be there anymore (create
            lava, decline to die, and get teleported away to safety) */
         if (u.uinwater && !is_pool(u.ux, u.uy)) {
-            u.uinwater = 0; /* leave the water */
+            set_uinwater(0); /* u.uinwater = 0; leave the water */
             docrt();
             /* [block/unblock_point was handled by docrt -> vision_recalc] */
         } else {
diff --git a/src/save.c b/src/save.c
index 1bde78213..f7af31a9d 100644
--- a/src/save.c
+++ b/src/save.c
@@ -104,7 +104,7 @@ dosave0()
     if (iflags.save_uswallow)
         u.uswallow = 1, iflags.save_uswallow = 0;
     if (iflags.save_uinwater)
-        u.uinwater = 1, iflags.save_uinwater = 0;
+        u.uinwater = 1, iflags.save_uinwater = 0; /* bypass set_uinwater() */
     if (iflags.save_uburied)
         u.uburied = 1, iflags.save_uburied = 0;
 
diff --git a/src/trap.c b/src/trap.c
index 0d5514d10..8d84e88cd 100644
--- a/src/trap.c
+++ b/src/trap.c
@@ -3805,7 +3805,7 @@ drown()
             placebc();
         }
         vision_recalc(2); /* unsee old position */
-        u.uinwater = 1;
+        set_uinwater(1); /* u.uinwater = 1 */
         under_water(1);
         g.vision_full_recalc = 1;
         return FALSE;
@@ -3871,7 +3871,7 @@ drown()
         /* still too much weight */
         pline("But in vain.");
     }
-    u.uinwater = 1;
+    set_uinwater(1); /* u.uinwater = 1 */
     You("drown.");
     for (i = 0; i < 5; i++) { /* arbitrary number of loops */
         /* killer format and name are reconstructed every iteration
@@ -3890,7 +3890,7 @@ drown()
         pline("You're still drowning.");
     }
     if (u.uinwater) {
-        u.uinwater = 0;
+        set_uinwater(0); /* u.uinwater = 0 */
         You("find yourself back %s.",
             Is_waterlevel(&u.uz) ? "in an air bubble" : "on land");
     }
diff --git a/src/zap.c b/src/zap.c
index 8128d1064..192e32fac 100644
--- a/src/zap.c
+++ b/src/zap.c
@@ -4514,7 +4514,7 @@ short exploding_wand_typ;
                 if (x == u.ux && y == u.uy) {
                     if (u.uinwater) { /* not just `if (Underwater)' */
                         /* leave the no longer existent water */
-                        u.uinwater = 0;
+                        set_uinwater(0); /* u.uinwater = 0 */
                         u.uundetected = 0;
                         docrt();
                         g.vision_full_recalc = 1;